bike running great but oil coming from exhaust

Hey guys, so I've had a post on here about the possible failure of my valve guide oil seals but talking to a knowledgeable source, I believed the source of an in cylinder oil leak to be the o ring that seals the oil gallery going from the block to head. After doing ask that work to replace the ring, the bike starts up just fine. Runs great. But, there is a good amount of smoke coming from the right exhaust. Also, there seems to be actual oil coming from the exhaust as well. The bike doesn't seem to care though. Runs perfectly. The plug does look like it's seeing some oil but normally it would foul. Any ideas?

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Sorry I did this on my phone and thought it was already listed. Its a 1982 kz750 CSR twin. Me recent topics have been all about finding an oil leak which filled one cylinder and leaked through the exhaust. With help from bountyhunter, I tracked it down to the o rings on the oil passage from block to head. I rebuild the head with new valve guide oil seals, new head gasket, and the replaced those o rings.

I have it back together now and it immediately starts burning oil. Oil coming out of the exhaust (not at the head like last time, only out the back of the pipe) and the plug does seem to have oil on it but it doesn't foul like normal. Just at a loss because it should be sealed but leak is worse after all new seals?? Also, I changed the oil to rotella t don't know if that makes any difference.

Any info on where to get new rings? I think that my problem is worn rings because it smokes more under acceleration. just seems like its going to be difficult to locate a good source of these parts..

Could perform a compression test.
Could also perform a poor man's leak-down test (see * below).
But neither test will provide much direct evidence as to condition of the "oil" rings.

With header pipes removed, and looking into the exhaust ports, is there any evidence of oil inside the ports that might be draining down past damaged exhaust valve stem seals?
Such oil from the crankcase could collect inside the exhaust system and partially burn on its way out (producing blue smoke similar to the exhaust smoke produced due to worn or damaged oil rings, or an improperly installed oil ring).

*
A leak-down test injects air pressure through the spark plug hole to pressurize the combustion chamber.

Can perform a poor man's leak-down test by introducing compressed air into a spark plug hole and listening to where it escapes from the combustion clamber. This may be done at TDC or any other cam positions where both valves are fully closed. Top dead center (TDC) is when the piston is at its highest position. An easy way to tell TDC is by alignment of the T mark with the case mark when viewed through the timing window.

May introduce a spurt of compressed air by using a rubber cone-tip blow gun (rubber air nozzle) held into the spark plug hole. And of course keep holding it in position to keep air from coming back out the spark plug hole while listening for escaping air at other places. The air compressor should not be running while listening because the noise will likely drown out any sound of escaping air. Or just use a portable compressed air tank.

Air heard escaping from exhaust port indicates exhaust valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from carb intake indicates intake valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from crankcase breather indicates loss of compression past rings into crankcase (perhaps worn piston rings or cylinders).

Air heard escaping from head gasket area indicates indicates loss of compression past head gasket (perhaps due to a blown head gasket).

A leaking valve may sometimes be resolved by adjusting the clearance to within specs.

A leaking head gasket may sometimes be resolved by torquing the head fasteners when the engine is stone cold (such as after sitting overnight).

Good Fortune!

If needed, the link below is to a site where a service manual may be downloaded.

kz750twins.com/?p=15

Good Fortune!

bpchura wrote: Any info on where to get new rings?.

I see new piston/ring sets on ebay a lot for the 750 twins and the prices are a lot cheaper than for the four cylinder bikes.

You should find out if the cylinder wall has a serious problem. It may mean you will need to bore it up a size or get a good uses cylinder. The pistons and rings come in larger sizes that go up 0.5mm and 1.0mm.

You can also search Google for a DIY leak down tester. Much cheaper than buying one. Auto zone has free rental tools with deposit I believe some of then have leak down testers, most of them carry compression testers. Good luck.

I've got eBay rings in my bike, and am having terrible luck getting the oil control rings to seat(they are getting better, but slowly). I would suggest trying to source new rings from wiesco. A PM to member "larryc" would not be a waste of time. Ape might have what you need as well.

Thanks for all these reply's guys. In response to patton, I am pretty sure that I have all the leaks taken care of. I ran a compression test and did get about 170 lbs on both cylinders. The head gasket is new and properly torqued so head gasket should be leak free. I also replaced the valve guide oil seals so I highly doubt that those could be the issue. I am thinking it is is the rings just because I have exhausted all other options. It smokes a little at idle but increases with throttle. Its only on one side too which leads me to believe that its the oil rings.

Just thought of this though... This bike has been running really well.. It had top notch compression and has never had issues with anything related to the rings. On my last posts, the bike was out of comission because oil was leaking into the same cylinder that has issues now causing the plug to fowl, oil to blow out the exhaust, and the bike run on ony cylinder. I thought it was first the valve guide oil seals but I replaced those and had the same problem after about 300 miles. Then I tracked it down to the o ring on the oil passage to the head. It was old and I had overlooked it before. I replaced that and put it all back together where I am now. Upon the first start, (started up right away ) it was smoking from the same cylinder but I just thought that was due to all the oil left in the pipe after the last break down. Could it be something related to the previous failures?? Because I had to make it home when it broke down last, I rode about 20 miles on the highway on one cylinder. The problem cylinder being hauled along blowing oil around. Could that have done something to the rings? Could that cause the rings to bind or somehow leak?

Sorry for this long post but I would just like to explore the possibility that somehow the rings are laden with oil and that is why the smoking is present. Is there a way to investigate this further without doing any rebuilds?? thoughts??

With 170 psi on both cylinders the motor sounds pretty solid to me, are you sure its nots just oil that was already in exhuast getting burned/blown out of there?
Put a few miles on it and watch the oil level.